Well I did search on this subject, and several threads came up, lotta great info from Old Polack on multiple-boot set-ups. UncleV suggested a conglomeration of those threads/info and a sticky, I think that's a great idea!
I already have a dual-boot of windoze and Zen-Mini, thinking of adding another version of PCLOS to that, my current setup is thus:
fdisk -l
Disk /dev/sda: 100.3 GB, 100255211008 bytes
255 heads, 63 sectors/track, 12188 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x30273026
Device Boot Start End Blocks Id System
/dev/sda1 * 1 7649 61440561 7 HPFS/NTFS
/dev/sda2 7650 11856 33792727+ 83 Linux
/dev/sda3 11857 12188 2666790 82 Linux swap / Solaris
*Note that I used fdisk for info, Old Polack is gonna be so proud of me

...probably still have to use g-parted to make partition though, I likes my GUI!*
sda1 being Windows-NTFS
sda2 being Gnome Zen Mini PCLOS-ext3
sda3 is swap
I imagine I need to re-size the partition that the current PCLOS install is one, plenty of room to shrink it, and create new one. Would it be best to delete the swap partition first to maintain numbering sequence? That is, so the new partition could be "sda3", then make a new swap partition which would then become "sda4"?
Second question, assuming the partition issue is all sorted out, when I start to install the new PCLOS, will it automagically recognize the existing installs, and offer to install correctly and write the new selection properly to the existing grub menu? Or will it try to create it's own and/or wipe out the current one that exists on the current PCLOS install?
Thanks in advance for any tips/info!